This invention relates to an arrangement for disposing and driving a spinning rotor of an open-end spinning machine, which rotor is disposed with its rotor shaft in a wedge-shaped gap formed by two pairs of supporting disks. The rotor shaft is driven by a continuous belt looping around the rotor shaft between the pairs of supporting disks and pulling the rotor shaft into the wedge-shaped gap.
An arrangement of the above-noted type is disclosed in German Published Unexamined Application (DE-OS) No. 16 85 984 where the belt is driven by a driving pulley arranged on a shaft passing through in the longitudinal direction of the machine and driving, in the same manner, the spinning rotors of the plurality of individual spinning units arranged on one side of the machine. A very costly mechanism is provided for the guiding and tightening of the respective belts. In the case of such a drive, it is difficult to stop an individual spinning rotor and to start it again in a predetermined manner, for example, for repairing a yarn breakage.
In order to utilize the advantages concerning control and operation in the case of separate electric motor drives, it is also known from German Published Unexamined Application (DE-OS) No. 22 03 586 to dispose the shank or shaft of a spinning rotor in the wedge-shaped gap of pairs of supporting disks and to integrate it directly into an electric motor as the rotor. However, this construction was found in practice to be unsatisfactory because it results in considerable difficulties when, for example, the spinning rotor has to be exchanged. In the case of the known construction, this is possible only through costly assembly operations.
The invention is based on the objective of providing a simply constructed and uncomplicated arrangement of the initially mentioned type where the advantages of the easy exchange of the spinning rotor and of an individual drive are realized simultaneously.
This objective is achieved according to the invention by providing that the belt is looped around a driving pulley of an electric motor which, with respect to the pairs of supporting disks, is arranged in the area that is opposite the rotor shaft and which, for the tightening of the belt, is movably held in a guide in a plane that extends at least approximately through the wedge-shaped gap.
In the case of this arrangement of the present invention, a separate drive is assigned to each spinning rotor so that the resulting advantages with respect to the control and operation are maintained. At the same time, the arrangement is constructed in a very simple manner because the electric motor itself, by means of its movable mounting, takes over the tightening of the belt so that additional guiding or tightening devices for the belt are not required. Since the rotor shaft of the spinning rotor does not require complicated molding, the advantages concerning the easy exchange thereof are also maintained.
In an advantageous development of the invention, it is provided that the electric motor is held so that it can be pivoted around a shaft extending in parallel to the rotor shaft of the spinning rotor. This makes possible a very simple construction that ensures a very precise guiding.
In a further advantageous development of the invention, it is provided that the shafts of the pairs of supporting disks extend at least approximately horizontally, that the rotor shaft is placed in the wedge-shaped gap from above, and that the electric motor with the driving pulley is arranged below the pairs of supporting disks. As a result, it is ensured that the rotor shaft is held in the wedge-shaped gap without additional means when the drive is stopped. It is also achieved that the electric motor's own weight is used for the tightening of the belt.
In a further development of the invention, it is provided that the driving pulley of the electric motor is arranged to be laterally displaced with respect to the plane extending vertically through the wedge-shaped gaps and closer to the supporting disks following the driving pulley in the moving direction of the belt. This takes into account the circumstance that in the case of a belt drive, the load is not symmetrical because a larger force is transferred via the pulling end of the belt. By means of the displaced arrangement of the electric motor, the load to the rotor shaft and thus also to the supporting disks can be made more uniform.
In a further development of the invention, it is provided that the pairs of supporting disks are disposed in a joint bearing support having two bearing receiving means assigned to the bearings of the supporting disks; said bearing receiving means being connected with one another via a bridge reaching around the area to be taken up by the rotor shaft of the spinning rotor. This takes into account the fact that the precise positioning of the shafts of the supporting disks has considerable influence on the moving characteristics, especially when, by means of a slight offset of the shafts, the rotor shaft of the spinning rotor is intentionally to be subjected to an axial thrust. By means of the one-piece development of the bearing support, the desired alignments with respect to one another can be achieved with great precision already in the manufacturing plant, without allowing assembly-caused tolerances to have an effect.
In a further development of the invention, it is provided that the guide receiving the electric motor is mounted at the bearing support. As a result, it is achieved that the electric motor forms a constructional unit with the pairs of supporting disks that can be manufactured with high precision.
In a further development of the invention, it is provided that at the bearing support, a step bearing is mounted that receives the free end of the rotor shaft of the spinning rotor. As a result, a necessary step bearing for certain embodiments is also integrated into the constructional unit causing an axial fixing of the rotor shaft and thus of the spinning rotor.
In a further development of the invention, it is provided that the bearing support is fastened at a supporting part via elements made of a vibration-absorbing elastic material. As a result, a noise reduction can be achieved.
In a further development of the invention, it is provided that the rotor shaft of the spinning rotor is provided with a barrel-shaped enlargement in the starting area for the belt. By means of this enlargement, a favorable vibration behavior of the rotor shaft is achieved since the rotor shaft also has the largest cross-section in the area of its highest stress. In addition, the cambered enlargement also results in advantages with respect to the course of the belt.
In a further development of the invention, means are provided for braking the spinning rotor which, directed into the wedge-shaped gap, can be applied to the rotor shaft of the spinning rotor and which are coupled with the electric motor by means of pulling elements in such a way that, starting from an indicated movement of the electric motor directed away from the rotor shaft, the means for braking are applied to the rotor shaft. The means for braking the spinning rotor come in at least when a breakage of the belt should occur, in which case, the means for braking will then immediately take over the securing of the rotor shaft of the spinning rotor in the wedge-shaped gap so that the spinning rotor can carry out no uncontrolled movements.
In a further development of the invention, it is provided that the path of the electric motor away from the rotor shaft is limited by a limit stop. This ensures that in the case of a breakage of the belt, the path of the electric motor is restricted, so that no damage can occur by an uncontrolled movement of the electric motor.
In a further development of the invention, it is provided that means for stopping the electric motor that respond to a breakage of the belt and/or a change of the spun yarn are provided. These measures also have the purpose of further securing the spinning unit. In addition, it may be provided that these means are connected to a control light which can draw the attention of an operating person or of an automatic servicing apparatus to the spinning unit suffering from a disturbance.
In a further development of the invention, means for increasing or reducing the tension of the belt are provided that are applied to the electric motor and/or its holding means. These means may be used to achieve a balancing effect when the weight of the electric motor is too high or too low for a sufficient tension. It is also possible to increase the tension of the belt for a short time via these means, especially when the spinning rotor is accelerated from stoppage to an operational speed. Thus it becomes possible to reduce slippage of the belt.
In a further development of the invention, an actuating element is provided for actuating the means for braking the spinning rotor, said actuating element being coupled with the electric motor or its holding means in such a way that the electric motor is moved in the direction toward the rotor shaft of the spinning rotor during the braking. This ensures that the driving force for the rotor shaft is reduced during braking so that damages to the belt and/or the electric motor are avoided.
In a further development of the invention, means for holding the belt are provided at the bridge of the bearing support. These means are used as an aid during the mounting of the belt since the belt can then tentatively be held in a position in which the rotor shaft of the spinning rotor can be introduced in the wedge-shaped gap in a simple manner.
In a further development of the invention, means for receiving the belt are provided at the electric motor or its holding means which are arranged in proximity of the shank on the side facing the wedge-shaped gap. Thus it is achieved that, when the spinning rotor with its rotor shaft is removed, the belt does not hang about the unit in an uncontrolled manner but is taken up by the receiving means, from where it can be removed in a simple manner, when the shank of the spinning rotor is reintroduced.
In a further development of the invention, it is provided that the supporting disks of the pairs of supporting disks are displaced axially with respect to one another and are arranged so that they overlap one another radially. This results in a compact space-saving construction.
In a further development of the invention, it is provided that the electric motor has a flat-angle accelerating curve and a flat-angle braking curve. This reduces the slippage of the belt so that durability is increased. Generally, an accelerating time or braking time of two to three seconds can be considered as sufficient according to preferred embodiments of the invention.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.